What is the difference between E26, E27 and A19?

What is the difference between E26, E27 and A19?

What is the difference between E26 and E27 lamp base types?

When shopping for LED light bulbs, you'll notice unique terms such as E26 and E27. If your not aware of what these terms mean it can overly complicate your shopping experience.

Most people are familiar with screw in bulbs that feature a lamp base called an Edison Screw, or ES for short. Fun fact, this base was originally developed by Thomas Edison back in 1879 and is still the most commonly used base for light bulbs today.

There are four primary thread sizes for lamp bases.

  • Candelabra: E12 in North America, E11 in Europe
  • Intermediate: E17 in North America, E14 (Small ES, SES) in Europe
  • Medium or Standard: E26 (MES) in North America, E27 (ES) in Europe
  • Mogul: E39 North America, E40 (Goliath ES) in Europe

So, what do the numbers after the E mean? The numbers designate the what the size of the external thread screw is in mm. For example, a bulb with an E26 base has a diameter of 26 mm.

Now, you may have noticed LED bulbs with an E27 base for sale from retailers that are advertised to work in fixtures that have an E26 base. Even though that statement is completely true, more than likely these bulbs were manufactured by foreign suppliers and could possibly lack the proper North American, UL or ETL safety certification. Therefore, these bulbs should not be used if you reside in North America.

What does A19 mean?

The letter "A" designation describes the shape of the light bulb and the number that follows indicates the diameter of the bulb in one-eight inch units, or in millimeters.

The most commonly used A-series light bulb is the A19 bulb, which is 2 3/8 inches (60 mm) wide at its widest point and approximately 4 3/8 inches (110 mm) in length. This is the classic shape that most people are accustomed to when shopping for a "Light Bulb".


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